Such a toothbrush is known from U.S. Pat. No. 3,859,684.
This known toothbrush comprises a rotatable brush having a brush shaft pivotably connected to a drive shaft by means of a universal joint, the drive shaft being situated in a first housing section. The brush shaft is enclosed by a second housing section, which projects into the first housing section. A switching spring is arranged between the housing sections to turn on the motor when the second housing section is pivoted relative to the first housing section during use.
The force with which the brush is pushed against the teeth is important for a proper cleaning action. To remove dental plaque a certain pressure must be applied. However, the brushing pressure should not be too high because the brush also comes into contact with, for example, the gums and the tooth necks during brushing. The tooth brush in accordance with U.S. Pat. No. 3,859,684 does not provide such protection.